Differential Molecular Modeling Predictions of Mid and Conventional Dialysate Flows

2019 ◽  
Vol 47 (4) ◽  
pp. 369-376
Author(s):  
John K. Leypoldt ◽  
Sarah Prichard ◽  
Glenn M. Chertow ◽  
Luis Alvarez
Keyword(s):  
Small Difference ◽  
Urea Clearance ◽  
Additional Time ◽  
Flow Rates ◽  
Dialysate Flow ◽  
Typical Treatment ◽  
Few Data ◽  
Kinetics Of ◽  
Conventional Hemodialysis ◽  
Volumes Of Distribution

Background: High dialysate flow rates (QD) of 500–800 mL/min are used to maximize urea removal during conventional hemodialysis. There are few data describing hemodialysis with use of mid-rate QD (300 mL/min). Methods: We constructed uremic solute (urea, beta2-microglobulin and phosphate) kinetic models at varying volumes of distribution and blood flow rates to predict solute clearances at QD of 300 and 500 mL/min. Results: Across a range of volumes of distribution a QD of 300 mL/min generally yields a predicted urea spKt/V greater than 1.2 during typical treatment times with a small difference in urea spKt/V between a QD of 300 and 500 mL/min. A larger urea KoA dialyzer and 15 min of additional time narrows the urea spKt/V difference. No substantial differences were observed regarding the kinetics of beta2-microglobulin and phosphate for QD of 300 vs. 500 mL/min. Conclusion: A QD of 300 mL/min can achieve urea clearance targets. Hemodialysis systems using mid-rate QD can be expected to provide adequate hemodialysis, as currently defined.

Clearance of Levofloxacin by an in Vitro Model of Continuous Venovenous Hemodialysis (CVVHD)

2007 ◽  
Vol 30 (10) ◽  
pp. 889-895 ◽  
Author(s):  
S. Siewert ◽  
B. Drewelow ◽  
S.C. Mueller
Keyword(s):  
In Vitro Model ◽  
Urea Clearance ◽  
Flow Rates ◽  
Dialysate Flow ◽  
Dialysate Flow Rate ◽  
Continuous Venovenous Hemodialysis ◽  
Vitro Model ◽  
Positive Correlations

Information about the elimination and the adequate dosing of levofloxacin during renal replacement therapy is scarce. The aim of this study was to characterize in vitro the elimination of levofloxacin during continuous venovenous hemodialysis (CVVHD) and to investigate whether the CVVHD clearances of creatinine and urea are correlated with the levofloxacin clearance in order to facilitate dosage adjustments. An in vitro model of CVVHD was established using five dialyzer membranes at varying dialysate flow rates applied in the clinical setting (8, 16, 25, 33 and 41 ml/min). Plasma and dialysate samples were drawn for determination of levofloxacin, creatinine and urea concentrations to evaluate clearances by CVVHD. During CVVHD, the clearance of levofloxacin varied between 9.02 and 33.30 ml/min, depending on the chosen setup. Positive correlations (p<0.001) were received for: dialysate flow rate (QD) and creatinine/urea clearances (R>0.93); QD and levofloxacin clearance (R 0.59–0.71); levofloxacin and creatinine clearance (R 0.69–0.75); and levofloxacin and urea clearance (R 0.56–0.75) as well. When dosing critically ill patients, therefore, extracorporeal as well as total clearance of levofloxacin should be considered.

The Effect of Hematocrit on the Clearance of Small Molecules during Hemodialysis

1983 ◽  
Vol 6 (3) ◽  
pp. 127-130 ◽  
Author(s):  
C. Woffindin ◽  
N.A. Hoenich ◽  
D.N.S. Kerr
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Small Molecules ◽  
Flat Plate ◽  
Flow Rate ◽  
Distribution Curve ◽  
Blood Flow Rate ◽  
Hollow Fibre ◽  
Urea Clearance ◽  
Flow Rates

Data collected during the evaluation of a series of hemodialysers were analysed to see the effect of hematocrit on the clearance of urea and creatinine. All evaluations were performed on patients with a range of hematocrits with a mean close to 20%. The urea clearance of those in the upper half of the distribution curve (mean hematocrit 29.4%) was not significantly different from that of patients in the lower half of the distribution curve (mean hematocrit 16.9%) whether the clearance was studied at high or low blood flow rates and with hollow fibre or flat plate disposable hemodialysers. Likewise, there was no correlation between hematocrit and urea clearance by regression analysis. In contrast, the clearance of creatinine was affected by hematocrit being greater at lower hematocrit values. This difference was independent of blood flow rate and dialyser type and was confirmed by regression analysis.

scholarly journals Kinetics of acid-base parameters in conventional hemodialysis

2019 ◽  
Vol 52 (1) ◽  
Author(s):  
J.R. Lugon ◽  
G.R.M. Pereira ◽  
J.P. Strogoff-de-Matos ◽  
A.J. Peixoto
Keyword(s):  
Acid Base ◽  
Base Parameters ◽  
Kinetics Of ◽  
Conventional Hemodialysis

scholarly journals Effect of dialysate potassium and lactate on serum potassium and bicarbonate concentrations during daily hemodialysis at low dialysate flow rates

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
John K. Leypoldt ◽  
Michael A. Kraus ◽  
Bertrand L. Jaber ◽  
Eric D. Weinhandl ◽  
Allan J. Collins
Keyword(s):  
Serum Potassium ◽  
Flow Rates ◽  
Dialysate Flow ◽  
Daily Hemodialysis

Conversion of Alkoxide Solutions to Oxides: Evaporation of Products

1989 ◽  
Vol 155 ◽  
Author(s):  
R. A. Lipeles ◽  
D. J. Coleman
Keyword(s):  
High Flow ◽  
Drying Rate ◽  
Flow Rates ◽  
Long Time ◽  
Drying Rates ◽  
Drying Conditions ◽  
Kinetics Of ◽  
By Products ◽  
Evaporation Kinetics ◽  
Kinetics Monitoring

ABSTRACTThe evaporation of organic by-products released during drying of 1-mm thick silicon tetramethoxide gels was analyzed using gas chromatography. The evaporation kinetics of methanol depended on the drying rate achieved by flowing dry air over the gel. For drying at flow rates less than 50 cm 3/min, exponential kinetics were observed initially with a long time constant (about 100- to 400-min). For drying rates greater than 70 cm3/min, diffusional (t−1/2) kinetics were observed initially. Cracking of the gel during drying was used to indicate the degree of stress. At low drying rates, minor cracking was observed near the edges of the gel. At high flow rates, extensive cracking was observed in samples that exhibited early t−1/2 kinetics. Monitoring the kinetics of drying is essential to optimizing the drying conditions to minimize stress and cracking in gels.

scholarly journals P1117EXPLORATORY COMPARISON OF DIALYSIS EFFICIENCY AT DIFFERENT DIALYSATE FLOW (QD) IN EXPANDED HEMODIALYSIS IN TWO CENTERS IN COLOMBIA

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Alejandra Molano Trivino ◽  
Eduardo Zúñiga ◽  
Mauricio Sanabria ◽  
Jasmin Vesga ◽  
Carolina Ramos ◽  
...  
Keyword(s):  
Recent Literature ◽  
Demographic Data ◽  
Reduction Rate ◽  
Interleukin 10 ◽  
Wilcoxon Test ◽  
Flow Rates ◽  
Dialysate Flow ◽  
Dialysate Flow Rate ◽  
Middle Molecules

Abstract Background and Aims Dialysate flow rate (Qd) has minimal effect in removal of molecules in hemodialysis, allowing to use lower amounts of dialysate with no effect in clearance of molecules. According to recent literature, Expanded hemodialysis (HDx) improves the clearance of middle size molecules, diminishing the effect of Qd in adequacy. We found no data about clearance at different dialysate flow rates in HDx. Our aim is to evaluate the clearance of middle molecules (beta 2 microglobuline [Mβ2], interleukin-6 [IL-6], interleukin-10 [IL-10 light chains (CLL-κ -λ) with HDx at different Qd using membranes TheranovaMR in patients with body weight less than 70 Kg. Method We performed an observational retrospective analysis of clearance of Mβ2, IL-6, IL-10, CLL-κ; CLL-λ in HDx using TheranovaMR filters with Qd 400 mL/min and 500 mL/min. We performed variance analysis, T student test and Wilcoxon test. Data were extracted from an HDx multicentric trial performed in Bogotá, Colombia in 2018. Results 11 (47%) patients received Qd 400 mL/min and 12 (52.1%) patients with Qd 500ml/min. Demographic data are included in table 1. We found no differences in reduction rate of mid-molecules. (Table 2) We found that lower water consume in the Qd 400 mL/min group, with water savings of 24 Liters/patient (13824 L in 12 weeks of follow up). (Table 3) Conclusion Expanded hemodialysis seems to allow diminishing Qd rate without changes in mid-size molecules clearance.

scholarly journals How the Neurotoxin β-N-Methylamino-l-Alanine Accumulates in Bivalves: Distribution of the Different Accumulation Fractions among Organs

Toxins ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 61
Author(s):  
Alexandra Lepoutre ◽  
Elisabeth J. Faassen ◽  
A. J. Zweers ◽  
Miquel Lürling ◽  
Alain Geffard ◽  
...  
Keyword(s):  
Digestive Gland ◽  
Dreissena Polymorpha ◽  
Soft Tissues ◽  
Target Organ ◽  
Organ Distribution ◽  
Tandem Mass ◽  
Clear Water ◽  
Few Data ◽  
Kinetics Of ◽  
Over Time

The environmental neurotoxin β-methylamino-l-alanine (BMAA) may represent a risk for human health. BMAA accumulates in freshwater and marine organisms consumed by humans. However, few data are available about the kinetics of BMAA accumulation and detoxification in exposed organisms, as well as the organ distribution and the fractions in which BMAA is present in tissues (free, soluble bound or precipitated bound cellular fractions). Here, we exposed the bivalve mussel Dreissena polymorpha to 7.5 µg of dissolved BMAA/mussel/3 days for 21 days, followed by 21 days of depuration in clear water. At 1, 3, 8, 14 and 21 days of exposure and depuration, the hemolymph and organs (digestive gland, the gills, the mantle, the gonad and muscles/foot) were sampled. Total BMAA as well as free BMAA, soluble bound and precipitated bound BMAA were quantified by tandem mass spectrometry. Free and soluble bound BMAA spread throughout all tissues from the first day of exposure to the last day of depuration, without a specific target organ. However, precipitated bound BMAA was detected only in muscles and foot from the last day of exposure to day 8 of depuration, at a lower concentration compared to free and soluble bound BMAA. In soft tissues (digestive gland, gonad, gills, mantle and muscles/foot), BMAA mostly accumulated as a free molecule and in the soluble bound fraction, with variations occurring between the two fractions among tissues and over time. The results suggest that the assessment of bivalve contamination by BMAA may require the quantification of total BMAA in whole individuals when possible.

Studies on the formation of Graphite-Ferric Chloride complexes: Kinetics of Formation

1953 ◽  
Vol 6 (3) ◽  
pp. 302 ◽  
Author(s):  
JA Barker ◽  
RC Croft
Keyword(s):  
Particle Size ◽  
Diffusion Coefficients ◽  
Small Difference ◽  
Critical Concentration ◽  
Activation Energies ◽  
Ferric Ions ◽  
Chloride Complexes ◽  
Hexagonal Packing ◽  
Kinetics Of Formation ◽  
Kinetics Of

A study has been made of the kinetics of the diffusion of anhydrous FeC1, in graphite. I t was found that this process can be represented for stages between 50 and 100 per cent. saturation of the graphite and at temperatures in the range 200 to 360 OC by a relation of the type δc/δt = D(δ2c/δr2 + δc/δ/r), providing the diffusion coefficient D is assigned several values for concentrations of occluded FeCl3 above and below a critical concentration. The value of the latter was found to be about two-thirds the saturation concentration of FeCl3 in graphite, this value apparently being the point at which open hexagonal packing of intercalated ferric ions is complete and a closer hexagonal packing commences. Values of the activation energies of occlusion for concentrations above and below two-thirds saturation were found from the relations of corresponding values of diffusion coefficients to temper- ature. The small difference between these activation energies which were of the order of 2 to 3 kcal is attributed to a cancelling of effects, thus the energy necessary to separate carbon lamellae in early stages of occlusion is offset in later stages by hindrance imposed on diffusing molecules by those already occluded. Reduction of particle size of graphite accelerated the occlusion of FeCl3.

Dialyzer Clearances and Mass Transfer-Area Coefficients for Small Solutes at Low Dialysate Flow Rates

ASAIO Journal ◽  
2006 ◽  
Vol 52 (4) ◽  
pp. 404-409 ◽  
Author(s):  
John K. Leypoldt ◽  
Craig D. Kamerath ◽  
Janice F. Gilson ◽  
Goetz Friederichs
Keyword(s):  
Mass Transfer ◽  
Flow Rates ◽  
Dialysate Flow
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